US6768373B2 - Circuit configuration for demodulating a voltage which is ASK modulated by altering the amplitude between a low level and a high level - Google Patents

Circuit configuration for demodulating a voltage which is ASK modulated by altering the amplitude between a low level and a high level Download PDF

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Publication number
US6768373B2
US6768373B2 US10/680,384 US68038403A US6768373B2 US 6768373 B2 US6768373 B2 US 6768373B2 US 68038403 A US68038403 A US 68038403A US 6768373 B2 US6768373 B2 US 6768373B2
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Prior art keywords
circuit
charging
voltage
charging circuit
level
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US10/680,384
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US20040066227A1 (en
Inventor
Mario Kupnik
Gebhard Melcher
Tobias Schlager
Walter Kargl
Ernst Neuhold
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Infineon Technologies AG
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Infineon Technologies AG
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Priority claimed from DE2001116874 external-priority patent/DE10116874A1/de
Priority claimed from DE2001116747 external-priority patent/DE10116747B4/de
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Publication of US20040066227A1 publication Critical patent/US20040066227A1/en
Assigned to INFINEON TECHNOLOGIES AG reassignment INFINEON TECHNOLOGIES AG ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: NEUHOLD, ERNST, KUPNIK, MARIO, KARGL, WALTER, MELCHER, GEBHARD, SCHLAGER, TOBIAS
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation
    • H04L27/06—Demodulator circuits; Receiver circuits

Definitions

  • the invention relates to a circuit configuration for demodulating a voltage that is ASK (amplitude-shift keying) modulated by altering the amplitudes between a low level and a high level.
  • ASK amplitude-shift keying
  • ASK modulation is often used. This is understood to mean a high-frequency signal that alternates between a first level and a second level using data available in digital form, and thus modulates the high-frequency signal.
  • ASK modulation when the distance between the sender and the receiver of a signal being modulated in this way changes while the amplitude of the transmitted signal is constant, the received amplitude at the receiver changes. The same applies if differences arise in the intervening space between the sender and the receiver.
  • the object of the invention is to provide a demodulator circuit, which reliably identifies the level change between two states during ASK modulation operations, and which has as little complexity as possible.
  • a circuit configuration for demodulating a modulated voltage having an amplitude alternating between a low level and a high level.
  • the circuit configuration includes a high-frequency input, and a rectifier circuit connected downstream of the high-frequency input.
  • the rectifier circuit has an output and an input for obtaining an input voltage.
  • the circuit configuration also includes a first charging circuit for producing a charging voltage and a second charging circuit for producing a charging voltage. The first charging circuit and the second charging circuit are connected in parallel to the output of the rectifier circuit.
  • the circuit configuration also includes a decoupling device for decoupling the charging voltage of the first charging circuit and the charging voltage of the second charging circuit when there is a prescribed ratio between the respective charging voltage and the input voltage for the rectifier circuit.
  • the circuit configuration also includes an evaluation circuit for ascertaining a modulation level from the ratio of the charging voltages.
  • the specified circuit has the advantage that it is a simple matter to identify the change in the modulation level when comparing the two charging voltages.
  • a floating current-mirror circuit for the first charging circuit and the second charging circuit.
  • a voltage transformer for changing the charging voltage of the first charging circuit and/or the is charging voltage of the second charging circuit.
  • a diode for coupling the first charging circuit and the second charging circuit when there is a predetermined ratio between the charging voltage of the first charging circuit and the charging voltage of the second charging circuit.
  • a voltage on the second charging circuit is converted into two different voltages.
  • the first charging circuit and the second charging circuit have different discharge times.
  • a charging-current amplification circuit and a changeover apparatus for turning on the charging-current amplification circuit from a prescribed degree of modulation onwards.
  • FIG. 1 is a diagram of a first exemplary embodiment of an inventive circuit configuration
  • FIG. 2 is a graph of the envelope for an ASK modulated signal
  • FIG. 3 is a graph of illustrative curves for the first and second charging voltages
  • FIG. 4 is a diagram of a second exemplary embodiment of the circuit configuration
  • FIG. 5 is a diagram of an example of an evaluation circuit
  • FIG. 6 is a graph of a characteristic discharge curve for Vref
  • FIG. 7 is a diagram of a circuit that implements the invention.
  • FIG. 8 is a graph of a characteristic charging curve for Vref.
  • FIG. 1 there is shown a first inventive exemplary embodiment of the invention, specifically a demodulator circuit, in which a high-frequency input voltage U HF is applied to the input of the demodulator circuit.
  • the input is denoted by the two input connections LA and LB.
  • FIG. 2 shows the envelope for the amplitude value of the high-frequency input voltage over time. As can be seen, it alternates between a high amplitude level, denoted by “high” and a low amplitude level, denoted by “low”.
  • This rectified high-frequency input voltage U HF is thus present in rectified form on the node Y shown in FIG. 1 .
  • the node Y has two charging circuits connected to it in parallel, which are is charged by the rectified high-frequency voltage.
  • the first charging circuit includes the capacitor C 1 and a current source i 1 , which are connected in parallel from the voltage node V 1 .
  • the second charging circuit includes the capacitor C 2 and the current source i 2 , which are connected in parallel from the current node V 2 .
  • the second charging circuit is connected to the node Y via a charging switch S 1 .
  • This switch S 1 is actuated with the low-frequency voltage U NF used to modulate the high-frequency AC voltage U HF . This is made possible in an extremely simple manner using a diode (not shown).
  • the time constant of the two charging circuits can be chosen such that it is high with respect to half the period of the high-frequency input voltage U HF 80 that the two input nodes V 1 and V 2 of the charging circuits experience no substantial voltage fluctuation (hum) caused by the zero crossings of the high-frequency AC voltage.
  • the amplitude of the high-frequency input voltage U HF is now intended to be at the “high” level up until the time before t 1 .
  • the switch S 1 turns off and the second charging circuit, and hence the input node V 2 , is decoupled from the rest of the circuit.
  • the time constants of the first and second charging circuits are chosen to be different, the two capacitors C 1 and C 2 discharge differently. This is possible, by way of example, by choosing the two capacitors C 1 and C 2 to be of the same size, whereas the current sources i 1 and i 2 are chosen to have different strengths.
  • the resultant discharge behavior is shown in FIG. 3 .
  • the voltage on the node V 2 drops much more sharply than the voltage on the node V 1 .
  • the voltage V 1 is again converted to a voltage at V 1 ′ by using a voltage divider X%. As can be seen in FIG. 3, this causes the discharge curves V 2 and V 1 ′ to intersect.
  • the point of intersection S is now suitable for identifying the passage from the “high” level to the “low” level.
  • An evaluation circuit ⁇ described later ⁇ can be used to detect such a point of intersection.
  • FIG. 4 shows another form of the inventive demodulator circuit.
  • V siglow the voltage on the node V 2 into two different voltages
  • V 2 ′′ also referred to as “V sighigh ”.
  • the circuit shown in FIG. 4 works, in principle, in exactly the same way as the circuit described with reference to FIG. 1 .
  • the time constant of the second charging circuit needs to be much lower than that of the first charging circuit, i.e. the current source i 2 discharges the capacitor C 2 much faster than the current source i 1 on the capacitor C 1 .
  • the switch S 1 turns on again. This means that the current source i 2 now additionally discharges the capacitor C 1 via the resistor R 1 . This can be identified from the fact that the discharge curve for V ref in FIG. 6 becomes steeper is from the time t 2 onwards. If the high-frequency voltage U HF now changes level from “low” to “high”, the capacitors C 1 and C 2 in the charging circuits are charged again and, as shown in FIG. 8, a point of intersection S′ is produced between the curve V ref and V siglow .
  • the diode D 3 ensures that in each case there is only a voltage difference corresponding to the voltage drop across this diode D 3 between V 1 and V 2 .
  • the voltage is carried in parallel on the two node points, even with large modulation swings, such as ASK 100 , where the amplitude of the high-frequency input voltage comes close to 0 volts for the “low” level. This ensures, even with these large modulation swings, that it is always possible to ascertain an accurate point of intersection between V sighigh and V ref .
  • FIG. 5 shows one possible evaluation circuit for the signals V ref corresponding to V 1 ′, V 2 ′ corresponding to V sighigh , and V 2 ′ corresponding to V siglow .
  • V 1 ′ is respectively applied to the negative input of two differential amplifiers
  • V sighigh and V siglow are respectively applied to the positive input.
  • the outputs of the differential amplifiers are connected to an RS flipflop, as shown.
  • the output of the RS flipflop then outputs a signal corresponding to a “high” level or to a “low” level.
  • Other evaluation circuits are also conceivable, however.
  • FIG. 7 shows the implementation of the invention in circuitry using customary CMOS technology.
  • the input AC voltage is also applied to the input connections LO and LD.
  • the diodes D 1 to D 2 in the preceding exemplary embodiments are formed using transistors N 4 and N 5 .
  • a floating current-mirror circuit including the p-channel transistors P 1 and P 0 is provided.
  • This current-mirror circuit charges the capacitors C 1 and C 2 , to which the current sinks including the n-channel transistors N 8 and N 10 are connected.
  • the ratio of the charging current delivered by the current-mirror circuit to the discharge current determines the respective charging time constant of the capacitors C 1 and C 2 .
  • the resistors R 4 , R 5 and R 7 realize the voltage dividers already explained in connection with the preceding exemplary embodiments. These voltage dividers deliver the signals V ref — dem , V sighigh and V siglow supplied to the window circuit.
  • the diodes N 24 and N 25 decouple the voltages V 1 and V 2 as soon as the input voltage drops below the voltage level of V 1 or V 2 .
  • the diode N 11 has the same function as the diode D 3 explained previously.
  • a corresponding control signal demodenx is supplied on the gate NA 6 .
  • This control signal operates the two parallel current sinks N 1 and N 0 connected in series with the current mirror P 4 .
  • the current mirror P 4 is in turn connected in parallel with the current-mirror circuits P 1 and P 0 , as a result of which the charging current of the capacitors is increased by a multiple. This ensures an unreduced detection bandwidth, since the steady state is restored in accelerated fashion even in the case of modulation with a large swing.
  • V refdem , V sigigh and V siglow are otherwise evaluated in a similar manner to that in the preceding exemplary embodiments.
  • the design variables for the circuit can be taken directly from the circuit.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Transceivers (AREA)
  • Near-Field Transmission Systems (AREA)
US10/680,384 2001-04-04 2003-10-06 Circuit configuration for demodulating a voltage which is ASK modulated by altering the amplitude between a low level and a high level Expired - Lifetime US6768373B2 (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
DE10116747 2001-04-04
DE10116874 2001-04-04
DE10116874.8 2001-04-04
DE2001116874 DE10116874A1 (de) 2001-04-04 2001-04-04 Schaltungsanordnung zur Demodulation in einer durch Wechsel der Amplitude zwischen einem niedrigen und einem hohen Pegel (ASK-) modulierten Spannung
DE2001116747 DE10116747B4 (de) 2001-04-04 2001-04-04 Schaltungsanordnung zur Demodulation einer durch Wechsel der Amplitude zwischen einem niedrigen und einem hohen Pegel (ASK-) modulierten Spannung
PCT/DE2002/000668 WO2002082634A2 (de) 2001-04-04 2002-02-22 Demoduliere für ämplitudenspungmodulierte (ask) signale

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2002/000668 Continuation WO2002082634A2 (de) 2001-04-04 2002-02-22 Demoduliere für ämplitudenspungmodulierte (ask) signale

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US20040066227A1 US20040066227A1 (en) 2004-04-08
US6768373B2 true US6768373B2 (en) 2004-07-27

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US (1) US6768373B2 (ko)
EP (1) EP1374514B1 (ko)
JP (1) JP3860795B2 (ko)
KR (1) KR100556222B1 (ko)
CN (1) CN1232085C (ko)
AT (1) ATE463111T1 (ko)
BR (1) BR0208564A (ko)
DE (1) DE50214314D1 (ko)
MX (1) MXPA03009074A (ko)
RU (1) RU2252492C1 (ko)
TW (1) TW569576B (ko)
WO (1) WO2002082634A2 (ko)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050219110A1 (en) * 2002-10-10 2005-10-06 Infineon Technologies Ag Circuit arrangement

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7545892B2 (en) 2002-08-22 2009-06-09 Infineon Technologies Ag Method and circuit for controlling the input signal for a contactless transponder
WO2004021270A1 (de) * 2002-08-22 2004-03-11 Infineon Technologies Ag Verfahren zum regeln des eingangssignals eines kontaktlos-transponders
FR2883434B1 (fr) * 2005-03-21 2007-04-20 Commissariat Energie Atomique Methode et dispositif de demodulation a deux niveaux.
KR20220041367A (ko) 2020-09-25 2022-04-01 삼성전자주식회사 정전기 보호 회로, 및 이를 포함하는 반도체 장치

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2751148A1 (fr) 1996-07-12 1998-01-16 Inside Technologies Demodulateur d'un signal alternatif module en amplitude recu dans une bobine par induction electromagnetique
EP0940769A1 (de) 1998-03-03 1999-09-08 Siemens Aktiengesellschaft Datenträger zum kontaktlosen Empfangen von amplitudenmodulierten Signalen
US6307428B1 (en) * 1998-11-05 2001-10-23 Infineon Technologies Ag Method for ASK demodulation, and ASK demodulator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2751148A1 (fr) 1996-07-12 1998-01-16 Inside Technologies Demodulateur d'un signal alternatif module en amplitude recu dans une bobine par induction electromagnetique
EP0940769A1 (de) 1998-03-03 1999-09-08 Siemens Aktiengesellschaft Datenträger zum kontaktlosen Empfangen von amplitudenmodulierten Signalen
US6323728B1 (en) 1998-03-03 2001-11-27 Infineon Technologies Ag Data carrier for the contactless reception of amplitude-modulated signals
US6307428B1 (en) * 1998-11-05 2001-10-23 Infineon Technologies Ag Method for ASK demodulation, and ASK demodulator

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050219110A1 (en) * 2002-10-10 2005-10-06 Infineon Technologies Ag Circuit arrangement
US7119610B2 (en) * 2002-10-10 2006-10-10 Infineon Technologies Ag Circuit arrangement

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Publication number Publication date
ATE463111T1 (de) 2010-04-15
CN1232085C (zh) 2005-12-14
US20040066227A1 (en) 2004-04-08
JP2004532564A (ja) 2004-10-21
BR0208564A (pt) 2004-03-30
CN1500332A (zh) 2004-05-26
MXPA03009074A (es) 2004-02-27
EP1374514A2 (de) 2004-01-02
EP1374514B1 (de) 2010-03-31
WO2002082634A3 (de) 2003-04-10
TW569576B (en) 2004-01-01
WO2002082634A2 (de) 2002-10-17
KR100556222B1 (ko) 2006-03-03
JP3860795B2 (ja) 2006-12-20
RU2252492C1 (ru) 2005-05-20
DE50214314D1 (de) 2010-05-12
KR20040008147A (ko) 2004-01-28

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